DiCaprio traumatised on movie set

The Titanic actor plays a tormented cop stuck in a hospital for the criminally insane in his fourth outing with director Martin Scorsese.

DiCaprio was put through gruelling scenes for the film, which involved being pelted with rats while having to remember complex dialogue.

And the experience took such an emotional toll on the star, DiCaprio started to lose his sense of reality.

He says, "My character was going through extreme emotional trauma and it's hard for those types of things not to rub off on you. Mark Ruffalo and I had to spout out three pages of dialogue. We had to talk through the wind machines, the rain machines and rats being thrown at us. But, just like the character, we had to persevere in finding out what was really going on in Shutter Island.

"A few weeks towards the end of filming, I started to forget where I was. We kept pushing this character further and further. It was day after day of re-enacting a traumatic event that was either a dream or reality for this guy. I remember saying to Marty, 'I have no idea where I am or what I'm doing.'"